The gut-brain connection and probiotic supplements

Studies support the use of probiotics to treat mood, cognition and other brain-related issues, but what does this say about the gut-brain connection?

The gut-brain connection is real

Nearly 80% of the studies concerning the effectiveness of antidepressants are funded by the pharmaceutical industry and most are favorable to their use.

According to the British Medical Journal, only about 40 to 60 out of 100 people who took an antidepressant noticed an improvement in their symptoms within six to eight weeks.¹ A report published in Psychotherapy and Psychosomatics states, “Meta-analyses of FDA trials suggest antidepressants are only marginally efficacious compared to placebos and document profound publication bias that inflates their apparent efficacy.”

Fortunately, science is beginning to look at mental health in a new way, and there is a lot of new research showing the gut-brain connection to depression and inflammation.^2,3 In addition, something as simple as dietary change can help patients with depression.^4-6 It makes sense; the brain is an organ just like the heart, the lungs or the liver, and it can be affected by inflammation, diet and lifestyle.

Target the microbiome

One possible source of inflammation is an unhealthy microbiome. One study found when friendly, commensal microbes set up residence inside the gut, their host produces T cells that maintain the health of the gut by counteracting inflammation.⁷ Targeting the microbiome with plant-based fiber and fermented foods positively affects the immune system⁸ and reduces inflammation.^9-11

There is a lot of research looking not only at the microbiome’s role in depression, but at brain function in general. Something as simple as probiotic supplementation has helped patients with major depressive disorder.^12,13 Bifidobacterium seems to be especially helpful. Specific strains have been studied. One study found using Lactiplantibacillus plantarum JYLP-326 could be an effective strategy to alleviate anxiety, depression and insomnia in test-anxious college students.¹³

Anxiety and depression are more prevalent in patients with inflammatory bowel disease. The authors of one study stated, “There is a high prevalence of symptoms of anxiety and depression in patients with IBD, with up to a third of patients affected by anxiety symptoms and a quarter affected by depression symptoms. Prevalence was also increased in patients with active disease: Half of these patients met criteria for anxiety symptoms and a third met criteria for depression symptoms. Encouraging gastroenterologists to screen for and treat these disorders might improve outcomes for patients with IBD.”¹⁵

The gut-brain connection to probiotic supplementation

Probiotic supplementation goes beyond addressing depression. One study looked at 63 subjects over the age of 65. They were given a placebo or probiotics containing Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 12 weeks. Brain-derived neurotrophic factor (BDNF) plays a fundamental role in neuronal survival, growth and plasticity, which is essential for learning and memory. BDNF also modulates neurotransmitters and regulates nervous system development throughout life. Those receiving the probiotic had an increase in BDNF. The probiotics group showed greater improvement in mental flexibility tests and stress scores than the placebo group.¹⁴ Probiotic supplementation helped not only with mood, but with cognition. Other research has also demonstrated cognitive improvement with probiotic supplementation.¹⁷

Dysbiosis may be a factor in autism. The authors of one study stated, “This meta-analysis suggests there is a dysbiosis in ASD children which may influence the development and severity of ASD symptomatology. Further studies are required to obtain stronger evidence of the effectiveness of pre- or probiotics in reducing autistic behaviors.”¹⁶

The gut-brain connection: It goes both ways

What is growing in the microbiome can affect the brain, but the opposite is also true. Thought and attitude can affect the microbiome. One study found cognitive behavioral therapy (CBT) improved the symptoms of irritable bowel syndrome. CBT affected the makeup of the microbiome and increased fecal serotonin levels.¹⁸

What to do

A lot of studies support the use of probiotics to treat mood, cognition and other issues involving the gut-brain connection. However, the intestines are an ecosystem. Therefore, in addition to recommending probiotic supplementation, encourage your patients to follow a sound nutritional plan, such as increasing vegetable fiber in their diet, increasing consumption of fermented foods and avoiding refined and processed foods. Encourage them to strictly avoid GMOs (glyphosate disrupts the microbiome) and eat organic foods whenever possible.

Final thoughts on the gut-brain connection

Your patients will benefit greatly from a holistic supplementation and nutritional approach to address a number of their health concerns.

PAUL VARNAS, DC, DACBN, is a graduate of the National College of Chiropractic and has had a functional medicine practice for 34 years. He is the author of several books and has taught nutrition at the National University of Health Sciences. For a free PDF of “Instantly Have a Functional Medicine Practice” or a patient handout on the anti-inflammatory diet, email him at paulgvarnas@gmail.com.

References

1. Barbui C, et al. Efficacy of antidepressants and benzodiazepines in minor depression: systematic review and meta-analysis. Br J Psychiatry. 2011;198(1):11-16. PubMed. https://pubmed.ncbi.nlm.nih.gov/21200071/. Accessed July 19, 2024.
2. Chang HH, et al. Treatment response and cognitive impairment in major depression: Association with C-reactive protein. Brain Behav Immun. 2012;26(1):90-95. PubMed. https://pubmed.ncbi.nlm.nih.gov/21839826/. Accessed July 19, 2024.
3. Krogh J, et al. The association between depressive symptoms, cognitive function, and inflammation in major depression. Brain Behav Immun. 2014;35:70-76. PubMed. https://pubmed.ncbi.nlm.nih.gov/24016864/. Accessed July 19, 2024.
4. Parletta N, et al. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression: A randomized controlled trial (HELFIMED). Nutr Neurosci. 2019;22(7):474-487. PubMed. https://pubmed.ncbi.nlm.nih.gov/29215971/. Accessed July 19, 2024.
5. Null G, Pennesi L. Diet and lifestyle intervention on chronic moderate to severe depression and anxiety and other chronic conditions Ther Clin Pract. 2017;29:189-193. PubMed. https://pubmed.ncbi.nlm.nih.gov/29122259/. Accessed July 19, 2024.
6. Francis HM, et al. A brief diet intervention can reduce symptoms of depression in young adults – A randomised controlled trial. PLoS One. 2019;14(10):e0222768. PubMed. https://pubmed.ncbi.nlm.nih.gov/31596866/. Accessed July 19, 2024.
7. Brown BD, et al. Intestinal microbiota-specific Th17 cells possess regulatory properties and suppress effector T cells via c-MAF and IL-10. 2023;56(12):2719-2735. https://www.sciencedirect.com/journal/immunity/vol/56/issue/12. Accessed July 19, 2024.
8. Wastyk HC, et al. Gut-microbiota-targeted diets modulate human immune status 2021;184(16):4137-4153. PubMed. https://pubmed.ncbi.nlm.nih.gov/34256014/. Accessed July 19, 2024.
9. Clark AK, et al. Edible plants and their influence on the gut microbiome and acne. Int J Mol Sci. 2017;18(5):1070. PubMed. https://pubmed.ncbi.nlm.nih.gov/28513546/. Accessed July 19, 2024.
10. Bolte LA, et al. Long-term dietary patterns are associated with pro-inflammatory and anti-inflammatory features of the gut microbiome. 2021;70(7):1287-1298. PubMed. https://pubmed.ncbi.nlm.nih.gov/33811041/. Accessed July 19, 2024.
11. Fritsch J, et al. Low-fat, high-fiber diet reduces markers of inflammation and dysbiosis and improves quality of life in patients with ulcerative colitis. Clin Gastroenterol Hepatol. 2021;19(6):1189-1199. PubMed. https://pubmed.ncbi.nlm.nih.gov/32445952/. Accessed July 19, 2024.
12. Schaub AC, et al. Clinical, gut microbial and neural effects of a probiotic add-on therapy in depressed patients: a randomized controlled trial. Transl Psychiatry. 2022;12(1):227. PubMed. https://pubmed.ncbi.nlm.nih.gov/35654766/. Accessed July 19, 2024.
13. Tian P, et al. Bifidobacterium breve CCFM1025 attenuates major depression disorder via regulating gut microbiome and tryptophan metabolism: A randomized clinical trial. Brain Behav Immun. 2022;100:233-241. PubMed. https://pubmed.ncbi.nlm.nih.gov/34875345/. Accessed July 19, 2024.
14. Kim C-S, et al. Probiotic Supplementation improves cognitive function and mood with changes in gut microbiota in community-dwelling older adults: A randomized, double-blind, placebo-controlled, multicenter trial. J Gerontol A Biol Sci Med Sci. 2021;76(1):32-40. PubMed. https://pubmed.ncbi.nlm.nih.gov/32300799/. Accessed July 19, 2024.
15. Barberio B, et al. Prevalence of symptoms of anxiety and depression in patients with inflammatory bowel disease: a systematic review and meta-analysis. Lancet Gastroenterol Hepatol. 2021;6(5):359-370. PubMed. https://pubmed.ncbi.nlm.nih.gov/33721557/. Accessed July 19, 2024.
16. Vazquez LI, et al. Composition of gut microbiota in children with autism spectrum disorder: a systematic review and meta-analysis. 2020;12(3):792. PubMed. https://pubmed.ncbi.nlm.nih.gov/32192218/. Accessed July 19, 2024.
17. Schneider E, et al. Effect of short-term, high-dose probiotic supplementation on cognition, related brain functions and BDNF in patients with depression: a secondary analysis of a randomized controlled trial. J Psychiatry Neurosci. 2023;48(1):E23-E33. PubMed. https://pubmed.ncbi.nlm.nih.gov/36653035/. Accessed July 19, 2024.
18. Jacobs JP, et al. Cognitive behavioral therapy for irritable bowel syndrome induces bidirectional alterations in the brain-gut-microbiome axis associated with gastrointestinal symptom improvement. 2021;9(1):236. PubMed. https://pubmed.ncbi.nlm.nih.gov/34847963/. Accessed July 19, 2024.